const title = document.getElementById('title')
// let timer = null
// title.addEventListener('keyup', function () {
//   if(timer) {
//     clearTimeout(timer)
//   }
//   timer = setTimeout(()=>{
//     console.log(title.value)
//     timer = null
//   }, 500)
// })


// 防抖
function debounce(fn, delay = 500) {
  let timer = null
  return function () {
    if(timer)clearTimeout(timer)
    timer = setTimeout(()=>{
      fn.apply(this, arguments)
      timer = null
    }, delay)
  }
}

title.addEventListener('keyup', debounce(function (){
  console.log(this.value)
}, 500))
